Rhyniognatha hirsti is not that simple an insect, since it has characteristics in common with winged insects; so, it's reasonable to assume that insects first appeared at an earlier time, probably in the Silurian period, which extends as far back as 445 million years ago.[1] A large radiation of insects, the beetles, occurred about 300 million years ago, and flying insects appeared about 250 million years ago.

Previously, fossilized pollen from flowers was found in the geologic record only since the Early Cretaceous, about 140 million years ago, so that time has been the earliest known for the existence of flowers. The present study pushes this date back 100 million years earlier.[3]

Middle Triassicpollen grains found in northern Switzerland. These grains were recovered from the Weiachcoresample at 950.82 meters (left) and 903.02 meters (right). The size of the left specimen is 32.0 x 46.0 μm, and the size of the right specimen is 31.5 x 41.5 μm. (Image sources, left and right, Peter A. Hochuli and Susanne Feist-Burkhardt, University of Zürich )

These data confirm a 2004 study by these same authors in which Middle Triassic pollen was found in cores from the Barents Sea, south of Spitsbergen. Says Hochuli, "We believe that even highly cautious scientists will now be convinced that flowering plants evolved long before the Cretaceous."[3]